Daniil Kvyat's displays in his first season for Toro Rosso have attracted the attention of Red Bull team boss Christian Horner.
The four-time constructors' champions promoted Daniel Ricciardo from the Italian-based junior outfit over the winter, having offered Formula 1 world champion Sebastian Vettel a drive in 2009.
If Red Bull do recruit a new driver it will likely be from Toro Rosso, who are a breeding ground for the team's junior driver programme, and Kvyat, a product of that programme, has impressed Horner with his pace so far in 2014.
He told Autosport: "He has been sensational and has been the rookie of the season so far. His raw pace and speed, considering the jump he has made from GP3, is hugely impressive.
"He had little pre-season testing and Jean-Eric [Vergne] is a very quick driver, so the benchmark he's up against is good as well."
Kvyat is currently five points behind his teammate in the drivers' rankings.
